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.TH NETDB.H 3HEAD "Sep 10, 2004"
.SH NAME
netdb.h, netdb \- definitions for network database operations
.SH SYNOPSIS
.LP
.nf
\fB#include <netdb.h>\fR
.fi

.SH DESCRIPTION
.sp
.LP
The <\fBnetdb.h\fR> header defines the type \fBin_port_t\fR and the type
\fBin_addr_t\fR as described in \fBin.h\fR(3HEAD).
.sp
.LP
The <\fBnetdb.h\fR> header defines the \fBhostent\fR structure that includes
the following members:
.sp
.in +2
.nf
char *h_name          /* official name of the host */
char **h_aliases      /* pointer to an array of pointers to
                         alternative host names, terminated
                         by a null pointer */
int  h_addrtype       /* address type */
int  h_length         /* length, in bytes, of the address */
char **h_addr_list    /* pointer to an array of pointers to
                         network addresses (in network byte
                         order)for the host, terminated by a
                         null pointer */
.fi
.in -2

.sp
.LP
The <\fBnetdb.h\fR> header defines the \fBnetent\fR structure that includes the
following members:
.sp
.in +2
.nf
char      *n_name     /* official, fully-qualified */
                         (including the domain) name
                         of the network */
char      **n_aliases /* pointer to an array of pointers to
                         alternative network names, terminated */
                         by a null pointer */
int       n_addrtype  /* the address type of the network */
in_addr_t n_net       /* the network number, in host byte order */
.fi
.in -2

.sp
.LP
The <\fBnetdb.h\fR> header defines the \fBprotoent\fR structure that includes
the following members:
.sp
.in +2
.nf
char *p_name         /* official name of the protocol */
char **p_aliases     /* pointer to an array of pointers to
                        alternative protocol names, terminated
                        by a null pointer */
int  p_proto         /* protocol number */
.fi
.in -2

.sp
.LP
The <\fBnetdb.h\fR> header defines the \fBservent\fR structure that includes
the following members:
.sp
.in +2
.nf
char *s_name         /* oficial name of the service */
char **s_aliases     /* pointer to an array of pointers to
                        alternativeservice names, terminated by
                        a null pointer */
int  s_port          /* port number at which the service
                        resides, in network byte order */
char *s_proto        /* name of the protocol to use when
                        contacting the service */
.fi
.in -2

.sp
.LP
The <\fBnetdb.h\fR> header defines the macro \fBIPPORT_RESERVED\fR with the
value of the highest reserved Internet port number.
.sp
.LP
The <\fBnetdb.h\fR> header provides a declaration for \fBh_errno\fR:
.sp
.LP
extern int h_errno;
.sp
.LP
The <\fBnetdb.h\fR> header defines the following macros for use as error values
for \fBgethostbyaddr()\fR and \fBgethostbyname()\fR:
.sp

.sp
.TS
l l
l l .
\fBHOST_NOT_FOUND\fR	\fBNO_DATA\fR
\fBNO_RECOVERY\fR	\fBTRY_AGAIN\fR
.TE

.sp
.LP
Inclusion of the <\fBnetdb.h\fR> header may also make visible all symbols from
\fBin.h\fR(3HEAD).
.SH ATTRIBUTES
.sp
.LP
See \fBattributes\fR(7) for descriptions of the following attributes:
.sp

.sp
.TS
box;
c | c
l | l .
ATTRIBUTE TYPE	ATTRIBUTE VALUE
_
Interface Stability	Standard
.TE

.SH SEE ALSO
.sp
.LP
.BR Intro (3),
.BR in.h (3HEAD),
.BR endhostent (3NSL),
.BR endnetent (3SOCKET),
.BR endprotoent (3SOCKET),
.BR endservent (3SOCKET),
.BR endhostent (3XNET),
.BR endnetent (3XNET),
.BR endprotoent (3XNET),
.BR endservent (3XNET),
.BR attributes (7),
.BR standards (7)
